Effect of power plant operating conditions on fly ash and bottom ash composition: a case study from power plant in Lampung

Fly ash and Bottom ash (FA-BA) are solid waste produced from the coal-generated power plant. FA consists of fine powder particles with diameters varying from 0.5-100 µm, while BA consists of coarser particles with a diameter of 0.125-2 mm. FABA and feed coal samples were collected from the power plant in Lampung to distinguish the effect of power plant operating conditions on FABA composition. Feed coal characteristics were examined by proximate and petrography analysis. Organic and inorganic components of FABA were identified using petrography analysis, while the detailed mineralogical composition of FABA was determined using X-Ray diffraction analysis. Moreover, major oxides of the feed coal and FABA were determined using inductive ICP-AES. From the analysis, it was found that FA composition is mainly organic material in the form of unburned carbon (UC). The abundance of UC content (up to 74.68%) indicates the inefficiency of the coal combustion process. In terms of inorganic, quartz is the most abundant mineral found in the FABA sample, up to 50.15%, in contrast to the glass content that was only 17.41%. A minor amount of spinel (0.03-2.00%) was found associated with Fe-oxide mineral. Kaolinite was only found in the BA sample from a landfill source and interpreted as external input from the dumping ground. The high content of UC and quartz will decrease the compressive strength of the material construction product providing a negative impact on the utilization of FABA.